NEWS OF THE WEEK
CURBING HUNGER WITH MICROBES Mice slim down with Nacylethanolaminemaking bacteria.
ACS MEETING NEWS: Genetically engineered bacteria keep mice slim
T
HERE’S A NEW FRONT in the battle of the
SHUTTERSTOCK
bulge. Scientists think reprogramming microbes in our guts might be the secret to achieving a slim stomach. Last year, researchers led by Vanderbilt University’s Sean S. Davies showed that mice fed bacteria genetically engineered to produce N-acylphosphatidylethanolamines, or NAPEs, stayed slimmer on a high-fat diet compared with mice that were fed different bacteria or none at all. NAPEs are produced naturally in the small intestine after food consumption and have been linked to feelO ings of fullness. “It appears that people who are obese OH N R don’t make enough of those compounds in response to H food, and that may be one of the reasons they tend to R = lipid overeat,” according to Davies. N-Acylethanolamine There is, however, some debate as to whether the
MODIFIED APPLE AND SPUD OKAYED MARKET-BOUND: FDA says engineered
versions are safe, nutritious
OKANAGAN SPECIALTY FRUITS
T
Arctic apples (right) are genetically modified to produce low levels of the enzyme that causes the fruit’s flesh to turn brown.
HE FOOD & DRUG ADMINISTRATION has
cleared the way for two genetically modified crops to hit the U.S. market—apples that resist browning and potatoes that produce less of the carcinogen acrylamide at high temperatures. The agency declared on March 20 that the crops are just as nutritious and safe as conventional apples and potatoes. The crops are controversial because they rely on a process called gene silencing, or RNA interference (RNAi). Although there is no evidence to suggest the products will pose a health or safety risk to humans or the environment, some consumer advocacy groups are raising concerns about the approval process. The modified apples were developed by Canadabased Okanagan Specialty Fruits under the name Arctic apples. This fruit contains added apple genes that code for an enzyme, polyphenol oxidase (PPO), that causes CEN.ACS.ORG
8
NAPEs themselves are responsible for suppressing appetites. Some scientists think N-acylethanolamines (NAEs), which are produced when enzymes in the small intestine break down NAPEs, actually curb hunger. Davies reasoned he could answer this question by creating bacteria that produce NAEs and comparing them with his NAPE-producing bacteria. In normal mice, he found that both NAPE- and NAE-producing microbes had similar slimming effects. But in mice that lacked the enzyme that converts NAPEs to NAEs, only the NAE-producing bacteria kept the mice thin. That result suggests that NAEs are really responsible for appetite suppression, and bacteria that produce them directly could be considered for curbing obesity, Davies said during a presentation in the Division of Medicinal Chemistry last week at the American Chemical Society national meeting in Denver. Steven M. Firestine, a pharmaceutical sciences professor at Wayne State University, commented, “Despite its importance in human diseases such as obesity, our ability to control hunger and satiety has been limited.” Davies’s work, he said, provides an interesting approach to this problem. “Although much work must be done to prove the efficacy and safety of this system,” Firestine said, “the approach taken by Davies has the potential to provide a long-term solution for the treatment of obesity in humans.”—BETHANY HALFORD
apple flesh to turn brown. The extra genes trigger RNAi, which inhibits expression of all genes that produce PPO. In Innate potatoes, developed by Idaho-based J. R. Simplot, gene silencing reduces the amounts of the amino acid asparagine and of reducing sugars in the spuds. At high temperatures, such as those used in frying, asparagine reacts with the sugars to form acrylamide, which has been shown to be carcinogenic in animal studies. FDA’s approval of the two crops spurred a coalition of advocacy groups to send letters to fast-food restaurants, urging them not to sell the modified apples and potatoes. The coalition warns of potential environmental, health, and economic risks associated with the products. They also raise concerns that the products won’t be labeled as containing genetically modified organisms (GMOs), saying that consumers have the right to know. Public confidence in GMO products is low because the GMO approval process “is badly flawed,” says Gregory Jaffe, biotechnology director at the Center for Science in the Public Interest. For the newly approved apple and potato, FDA evaluated data produced by the companies and encouraged voluntary consultations between the businesses and the agency. “Congress should pass legislation that requires new biotech crops to undergo a rigorous and mandatory approval process before foods made from those crops reach the marketplace,” Jaffe says. “Such a system would give consumers much greater confidence that all genetically engineered products have been independently reviewed and found to be safe,” he says.—BRITT ERICKSON
MARCH 30, 2015
